As current structures are becoming taller and larger, it is becoming more important to provide higher strength and improved workability. For reinforced concrete structures, steel frame structures, and steel framed reinforced concrete structures, etc., which have been in common use until now, a structure may be constructed by assembling mold forms and steel rods or steel frames, etc., and casting the concrete directly at the construction site, so that the construction times may be increased and the quality may be made less reliable. As an alternate to such structures, the steel plate concrete structure (hereinafter referred to as “SC structure”) is receiving attention, which is made by filling concrete inside steel plates so that the steel plates restrict the concrete, and which provides desirable properties in terms of strength, load-bearing, strain characteristics, and workability, etc.
The SC structure is a system in which concrete is filled in between two steel plates, with studs and tie bars, etc., arranged such that the concrete and the steel materials move together, so that the steel materials and the concrete may move as an integrated body. In particular, the SC structure can be utilized in the construction of large structures such as nuclear power plants, etc., to reduce construction times by way of modularization.
FIG. 1 illustrates a steel plate structure according to prior art, before the concrete is cast. Hereinafter, the steel structure made of steel plates, etc., before casting concrete in a SC structure wall will be referred to as a “steel plate structure.”
The SC structure wall constructed using a steel plate structure according to prior art may be formed by vertically arranging steel plates 102 at both surfaces of the wall that is to be formed, installing a number of studs 104 on the inner surfaces of the steel plates 102 in order to facilitate the attachment between the steel plates 102 and the concrete, connecting the two steel plates 102 using rod-shaped struts 106 so as to secure the two steel plates 102, and then casting concrete in the space between the steel plates 102. When the inside of the steel plates 102 is filled with concrete in the SC structure wall, even if a failure occurs in the concrete, the steel plates 102 continue to restrict the concrete, to provide a greater level of load-bearing. Also, as the concrete is placed inside the steel plates 102, the concrete can be prevented from being degraded by the external environment, so that the durability of the structure can be improved.
However, when using a steel plate structure according to prior art in forming a SC structure wall for a large structure, such as a skyscraper and a nuclear power plant, etc., the thickness of the wall having a SC structure may be increased, leading to spatial limitations. Also, due to the greater amount of loads that must be supported, the steel plates and concrete may have to be increased in thickness, where the greater thickness for the steel plates may lead to increased thermal deformations when welding the steel plates, as well as to a need for thermal post-treatment. In the case of a skyscraper or a nuclear power plant structure, in particular, the axial forces applied by the weight of the structure and the lateral forces caused by earthquakes must be resisted in an efficient manner, but as the concrete inside the steel materials has a low shear strength, the remaining shear strength has to be resisted by the steel plates. In order to bear the lateral forces caused by earthquakes, the thickness of the steel plates may have to be increased.
Also, when modularizing the steel plate structure according to prior art and assembling the modules on site to form a wall, the steel plates of the unit modules may be welded together to attach the unit modules, or extra plates or couplers may be used in addition to the welding of the steel plates to enhance the adhesion strength between the unit modules. However, the extra plates or couplers may be exposed at the exterior surface to degrade the appearance, and the addition of secondary work may lead to longer construction periods. Furthermore, temporary reinforcement material may have to be additionally attached during the transporting of the unit modules to the construction site, in order to prevent deformations in the steel plate structure.
When installing a bracket used for installing an external device, such as piping, etc., to the exterior of the SC structure wall, the bracket may be welded or coupled with bolts, but when a large external device having a heavy mass is installed to the bracket, local deformations may occur in the steel plate, and the load-bearing performance may be degraded, so that the external equipment may not be installed on the outside of the wall.
Also, when casting concrete in the steel plate structure according to prior art, since the two steel plates are connected only by the rod-like struts, there is a risk that the steel plates may be deformed by the transverse pressure of the unhardened concrete.